Arrangement for multiplex radiofrequency traffic over high potential lines



Dec. 31, 1935. uRs'r 2,026,114

ARRANGEMENT FOR MULTIPLEX RADIOFREQUENCY TRAFFIC OVER HIGH POTENTIAL LINES Filed May 13, 1929 2 Sheets-Sheet 2 J5 j'g-7 I mpcon N655 INVENTOR WALTER wuRs ATTORNEY Patented Dec. 31, 1935 UNITED STATES ARRANGEMENT FOB Mmmrmx na'nro- FREQUENCY TRAFFIC oven men ro- TENTIAL LINES Walter Wurst, Berlin, Germany, assignorjo Telefunken Gesellschaft fiir Drahtlose Telegraphic m. b. 11., Berlin, Germany, a. corporation of Germany Application May 13, 1929, Serial No. 362,790 In Germany May 12, 1928 11 Claims.

(Granted under the provisions of Sec. 14, act of March 2, 1927; 3570. G. 5)'

The present invention is concerned with an arrangement for radio frequency multiple trafllc on high potential lines, especially over the identical phase or wire by way of joint coupling condensers, for intelligence transmission or any other form of communication, such as telemetric. or telecontrol purposes.

Compared with radio frequency telephony on ordinary telephone circuits and the arrangements used in connection therewith, the circuit schemes used for the present purpose present fundamental differences owing to the necessity of inserting high potential condensers between the high potential line and the radio frequency apparatus. This fundamental distinction necessitates the useof different arrangements. From an economic viewpoint, the general aim of the present invention is to insure multiple trafllc not only over one and the same conductor, but also by the use of joint high potential condensers.

The high potential condenser may be disposed as the first unit in a chain of.condensers, the

condition being that the surge or characteristic impedanceof the chain matches that of the high potential line, and that its liminal frequency falls below the maximum frequency required for the multiplex service. The output of this condenser chain would then, as regards surge impedance, be equivalent electrically to the input of the high potential line, with this difference, however, that it-has no dangerous high potential as used-in power transmission so that it allows readily of the connection of the radio frequency equipment just as in the case of radio frequency telephony over ordinary telephone lines. .However, high potential condensers that are of practical use have such a low capacitance that the conditions for adaptation to the frequency range or channel customary in radio frequency traflic over high potential lines can no longer be satisfied.

- Now, the present invention solvesthe problem fundamentally in this manner that the coupling to the high potential line for the different carrier frequencies is simultaneously based series resonance, in other words, the capacitiv resistance (capacitance) of the coupling condensers is simultaneously compensated for all carrier frequencies. Whenever the point is to unite high potential lines of different services (say, bridging of disconnecting switches, separating points, etc.) rather than the coupling of several radio frequency apparatus, for instance, telephone apparatus combined with telemetrlc or telecontrol apparatus to one high potential line, then the junction line permeable only to radio frequency is tuned according to the same basic rules. Unloaded chain systems are most united as tuning or phase compensating means, and these chain systems generally should be non-homogeneous in order to allow of any desired frequency adjust- 5 ment. As regards the impedance characteristics of its longitudinal (series) constitutents taken separately and of its transversal (shunt) constituents taken separately, the chain system most suitably is designed homogeneous or uniform, although the values of the different impedances may vary in conformity with the particular fre-, quency concerned.

The nature of the invention will be better understood from the following detailed description thereof and therefrom when read in connection with the attached drawings in which:

Figures 1 to 4 inclusive show diagrammatically,

v for purposes of illustration, my novel means for coupling a plurality of radio frequency apparatuses operating at diiferent frequencies to two or more transmission lines by way of a single high potential capacity for each line while Figures 5 to 9 inclusive show in detail portions of the circuits shown diagrammatically in Figures 1 and 4 inclusive which permit the application of multiplex traflic to high potential linesby way of a single high potential capacity for each line.

The tuning means used for tuning or phase compensation throughout the figures are designated by reference characters which include the letter A. Hence, the purpose of the same is to simultaneously compensate the capacitive resistance of the coupling condensers indicated by reference characters which include the letter .C for all carrier frequencies to be used so that above the same (that is to say, at the pointsmarked by a cross) the radio frequency means indicated by reference characters which include the letter G can be so connected as if they were directly connected in the high potentialconductors.

Now,'in the circuit arrangements here used,- the impedances contained at the input end of the radio frequency outfit may be utilized wholly or partly for the tuning of the coupler or iunction line so that in the corresponding circuit arrangements it will no longer be possible to flx definite points equivalent to the line points designated by a cross in the drawings.

The use of separate tuning means coordinated to each coupling capacity is recommendable particularly when the radio frequency apparatus must be joined with the coupling condensers through-more or less'long feeder wires, for in 65 this manner the radio frequency potentials on the feeder wires will be of a minimum amount and this makes for a reduction of losses.

In the scheme shown in Fig. 1, the radio frequency devices Gm which may comprise a combination of telephone apparatus with separate transmitter and receiver means as well as radio frequency telemetric and telecontrol apparatus, are placed in shunt relation to one another so that the compensation of the high potential'condensers can be accomplished each by means of a single tuning arrangement A. The tuning arrangement A1 or A2 may be complex in nature and portions thereof resonant at different frequencies, as will appear more in detail from the specification and more in particular from the description of Figures 5 to 9 inclusive..

Fig. 2 shows a modified parallel arrangement in which distinct tuning arrangements Am or Azn are coordinated to each radio frequency arrangement G11. for lines L1 and L2, respectively, said means A1n, Am being used both for tuning to the corresponding carrier frequency as well as for blocking out other carrier frequencies. Here the capacitive reactance of the coupling condensers is compensated while separation of frequencies is suitably efiected simultaneously by the-aid of the tuning means.

Of course, it is not absolutely necessary when using two lines L1 and L2 for radio frequency traflic to compensate the coupling condenser C1 and C2 for each line separately by tuning means.

. One such means could be made to do for both coupling condensers whenever symmetry in relation to ground is unessential. This will appear more clearly from the description of Figs. 7, 8, and 9 which follows.

As above pointed out the input impedances of the radio frequency apparatus Gn may be united and combined wholly or partly with tuning means A both in electrical as well as in constructional regard.

Referring to Figs. 1 and 2, S1 and Sz'denote the separating and grounding switches'customarily connected in air-line high potential systems by way of which the high potential lines L1 and L2 are connected to the station W (bus-bar, oil switches, potential transformers, etc.) These parts of the station, as is well known, mostly have a capacitive nature for radio frequency carrier currents, a fact brought out and indicated in the drawings by broken line condensers.

To make conditions independent of switching or circuit changing operations in station W and in the switches S1, it is imperative to insert stopper coils Sp which, for the sake of saving copper material are preferably tuned (combination of choke coils and capacities being in convenient galvanic or inductive relationship) to make conditions adapted at the same time to all carrier frequencies to be used. The connection of these tuned choke coils for all carrier frequencies should be chosen in perfect analogy with the other tuning means A1, A2, Am, Azn although in constructional regard an essential distinction exists insofar as the inductance inserted in the high potential phase must measure up to and be capable of handling large operating currents. However, in spite of this difference the fundamental arrangement later to be described for tuning means A1, A2, Am, Azn holds good also for these stopper coils Sp. Hence, looked at from this angle, the invention concerns also stopper coils connected in this manner.

Figs. 3 and 4 show exempliflcations of the radio KConditions must be so that radio frequency operation is feasible through and over this station even when some or all of the air lines separating (disconnecting) switches S1 and S: are opened and when the grounding switches are closed. Junction is established between the separate high potential lines by way of high potential condensers C1, C2 whose capacitance is compensated by the use of tuning means Am, An: previously referred to. When radio frequency equipment G15 comprising, for instance, radio frequency telephone apparatus or telemetric transmitters or receivers and the like are joined with the junction point, it is advisable to insure separate compensation of each'co'upling end in order that the 20 radio frequency potential along the entire feeder between the junction points may be diminished as far as feasible. If such radio frequency apparatus G are not connected at the junction point, then compensation of the two high potential con- 25 densers may be effected by the aid of only one tuning means. But if the connecting line of the high potential condensers is very long, then separate phase compensation directly at the high potential condensers is advisable.

Fig. 4 shows diagrammatically the junction between more than two high potential lines (Ln) worked under different service conditions.

Tuning means A1, A2, m are provided again for. the purpose of insuring compensation separately 35 for the condenser of each line so that the junction point designated by P will be at a minimum potential. If the different carrier frequenciesare not to be distributed uniformly, but if some branches are to be blocked for some of the car- 40 rier waves, then tuning means A1, A2, A: must also include circuits to act as stoppers for these particular frequencies. This is indicated in Fig. 4 wherein, for instance, the tuning device A1 allows of the passage of or insures compensation for all 45* of the frequencies in question, while tuning device A: passes or compensates only n-m frequencies, while blocking frequencies n1, whereas tuning device A: blocks n-m frequencies.

At the crossing point P, any desired radio fre 50 quency apparatus may be connected again.

Figs. 5 to 9 concern the tuning means A1, A2, A3. etc. and they illustrate the idea imderlying the invention,- namely, of using no-load chain systems or filters for multi-wave tuning. Any of 65 the tuning units of Figures 5 to 9 inclusive may be included in any of the tuning units A4, A2. Am, Am, and A1, A2, A3 of Figures 1, 2, 3, and 4.

The tuning units and line -L may be arranged as illustrated in Figure 5. Here the radio fre-, quency devices are coupled with an inductance L, the latter being inserted in the radio frequency feeder lead provided for connection with the high potential network L1 and L2. Connected in parallel with the said inductance L is an unloaded 65- filter network comprising series (longitudinal) resistances (impedances) x1, x: and shunt (transverse) impedances 11/1, 112. The impedances $1, at: have the inductance values required for compensation of the high potential condensers for 70 the different carrier frequencies. Here any number of frequencies may be impressed on the lines L1 and L2 by way of the two capacities C1: and: 0:. Two frequencies have-been used for purposes of illustration. In showing the manner in which 76 the circuit of Figure 5 may be tuned to impress efficiently two frequencies on the high potential lines L1 and L: by way of 'the'capacities C1 and C: suppose that shunt path 111 is short-.circuited temporarily. The variable reactanceelement x1 may be adjusted to produce resonance. in the circuit including the capacities C1 and C2 and the high tension line at frequency 11, which is the frequency of source G1. This adjustment will not be upset by any later variation of the elements in am because, since 111, L have been shortcircuited, no currentflows through the elements of 22. Now suppose the short-circuit is removed and that the shunt path 211 is so constructed or tuned as to present zero reactance to the currents of frequency h. This shunt path, being resonant at frequency f1, acts as a short-circuit for said frequencies and any variation of the elements in 1:: will not affect the tuning of the system includ-' tional impedances any number of frequencies may be impressed by resonant circuits which include the capacities C1, C: on to the lines La.

In the scheme shown in Fig. 6, the radio frequency apparatus G are coupled to separate inductances L1 and L2, while the radio frequency feeder line contains in parallel a condenser Cand a filter network by means of which multl-wave tuning is insured.

Hence, multi-wave tuning means designated,

generally as A essentially consist of the parallelconnection of an impedance (say, L in Fig. 5 or C in Fig. 6) and an unloaded filter network, the radio frequency equipment designated generally as G being coupled either with this parallel connection arrangement itself (Fig. 5) or with the feeder through separate'series connected impedances (see Fig. 6).

The tuning circuit of Figure 6 may be adjusted to give the proper response in the same manner in which the circuit of Figure 5 was-adjusted, as

set forth in detail hereinbefore.

Fig. 7 shows a particularly suitable tuning device comprising, as will be noted, a parallel connection of any convenient impedance 3 and an unloaded filter network whose longitudinal (series) impedances a1, a2, consist of. stopper circuits for the different carrier frequencies. This tuning means is connected in the radio frequency feeder line across the terminals pp of resistance .11. The provision of stopper circuits makes it possible to tune the tuning means by degrees or steps to the diflerent carrier frequencies. For instance, by the aid of impedance 1/ the feeder line can first be tuned to the highest carrier frequency, whereupon, after having adjusted the stopper circuits 21, 2: by steps bythe aid of the transversal resistances of thefllter network, the timing of-the feeder line to the other carrier frequencies can be continued by steps.

The tuning unit A may be adjusted as follows to provide the several frequency reronant paths which include the tuning capacities C1; Ca. Assume z; is tuned to present infinite impedance to I1. Arfiustment of the elements in 11 may change the character of the impedance of y to not be affected by later adjustment of elements 111. I However, 21 does not have an infinite impedance tov frequency is so that adjustment of element in will afiect the second natural frequency of the antenna system and may bring it to coincide 5 with the desired frequency 12. Additional units 2: and 1:: may be added, as shown, to tune the line to frequency 1:, etc. Furthermore, the units 21, 2: act as stopper circuits for certain of the frequencies with respect to other portions of the circuit.

The same end is attained also by an arrangement of the kind illustratedin Fig. 8- which is united with the feeder line by way of terminals pp. Here short-circuit paths in and u: are em- 15 ployed as shunt resistances in the unloaded network. For graduated multi-wave tuning in may first be shorted directly, whereupon the feeder line by the aid of an is tuned to a definite carrier frequency, say, the highest carrier frequency, whereupon, after the direct short-circuit of u; has been removed, this tuning can be restored by adjusting u; to series resonance. Tuning to the other carrier frequencies'is then continued by. stages in an analogous manner. In tuning the unit A of Figure 8 to resonance at several frequencie=, link a, is short-circuited, an is adjusted to tune the system including capacities'Ci, C: and inductance L to frequency "h. an will then be constructed or tuned to be series resonant at I frequency h after the short-circuit has been removed. m then presents zero reactance to {1. its is now shorted and :r: is timed so that the system including the inductance L and capacities C1, C2 resonates at the frequency f2. u: is then constructed or tuned so as to be series resonant at I: after the short-circuit around ua' has been removed. An additional impedance 2:: could be added and could be adjusted to tune the system including the-inductance L and the capacities 40 C1, C2 to the frequency is... Here, as in Figures .5 and 6, the process could be extended to include as many frequencies as desired. v v A modified scheme based upon a combination of resonance arrangements is illustrated in Fig. 9.4:; By means of the short-circuit m tuning to an extreme (limiting) carrier frequency is, first ef-' fected, then tuning is eflected to the next carrier frequency by the aid of m, whereupon to the other frequencies by stages just as in the case of Fig. 8. I Y

This network or tuning unit A is similar to thatk of Figure 7 and is tuned in the same manner in which the network of Figure 7 is tuned, as set forth in detail hereinbefore.

In order that as uniform as possible a distri-. bution of the losses may be insured for the various carrier waves, it is advisable to so dimension tuning means A when employed as series tuning means for the radio frequency junction hues (see so Figs. '7 and 8) that for lower frequencies they will act as an impedance, say, of positive nature, while for higher carrier frequencies as an imp danc of negative nature. I

Having now described my invention, what I in each connection, means in series in one of said connections to tune said connection includin said condenser to resonance at the frequency of one of said waves from said source, and an impedance in parallel with said tuning means, said impedance tuning said circuit toresonance at the frequency of another of said waves from said source.

2. An arrangement as claimed in claim 1 in which said means in one of said connections to tune said connection including said capacity comprises, an impedance and capacity in series.

3. An arrangement for impressinga plurality of carrier frequencies on to a pair of high potential lines comprising, a source of signalling waves of different frequencies, an impedance, coupling means between said impedance and said source, a connection between said impedance and each of said lines, there being a high potential condenser in each of said connections, a first tuning circuit connected with one of said connections to tune said connection and the high potential condenser therein to resonance at the frequency of one of said waves from said source, and a second tuning circuit connected with said first tuning-circuit to tune said first tuning circuit, said high potential condensers, and said connection to resonance at the frequency of another wave from said source.

4. A device as claimed in claim 3 in which there are n frequencies developed by said source and n tuning circuits connected with said impedance when n equals any desired number.

'5. In a multiplex system, a pair of, high potential lines, a source of signalling waves of different frequencies, an impedance coupled to said source, a connection including a high voltage condenser between one terminal of said impedance and one of said high frequency potential lines and a simi in connection from the other terminal of said impedance to the other of said high potential lines, and a variable reactance in shunt with-said impedance for tuning the circuit including said connections and the high voltage condensers therein to resonance at the different frequencies of said source.

- 6. In a multiplex system, a pair of high potential lines, a source of signalling waves of different frequencies, an impedance coupled to said source, a connection including a high voltage condenser between each terminal of said impedance and each of said high potential lines, and a variable-reactance in shunt with said impedance for tuning the circuit including said connections and the high voltage condensers therein to resonance at the different frequencies of said source, and means in series with said variable reactance and located between said reactance and said impedance for preventing the passage of waves of undesired frequencies. a

'7. In a multiplex system, a pair of high potential lines, a high voltage condenser connected to each line, a circuit including an inductance coil coupling together said two high voltage condensers, a plurality of high frequency generators electro-magnetically coupled to said one coil, and a network directly connected across said coi including tuning elements for enabling said sys- 5 tem comprising the high voltage condensers and net work to resonate at the frequencies of the oscillations generated by said high frequency generators.

' 8. In a multiplex system, a pair of high'potential lines, a high voltage condenser directly connected to each line on said pair, a series circuit coupling said condensers together comprising two inductance coils serially connected together through a condenser, a source of oscillations of coupling said condensers together comprising two inductance coils serially connected together through a condenser, a source of oscillations of one frequency coupled to one of said coils and a source of oscillations of another frequency coupled to the other of said coils, an unloaded network of capacity and inductance coupled across said last condenser, said network functioning to tune the series circuit and the highvoltage condensers to resonance at the frequencies of the two sources of oscillations.

10. In a multiplex system, a pair of high po.-- tential lines, a high voltage condenser directly connected 'to each line of said pair, a source of signalling waves of different frequencies, an unloaded T-type network consisting of series and shunt impedances connecting each terminal of said source to one of said high voltage condensers, each of said networks being so adjusted that for all of the frequencies of said signalling waves the fall of potential across its directly connected high voltage condenser is compensated.

11. In a multiplex system, a pair of high potential lines, a high voltage condenser individual to and directly connected to each line of said pair, a source of signalling waves of difle'rent frequencies coupled to said condensers, a network comprising a combination of capacity and induc- 55 tance tuning elements in circuit with said source and directly connected to one of said high voltage condensers, the elements of said network being so adjusted that for all of the frequencies of said signalling waves the fall of potential across its 6 directly connected high voltage condenser is compensated.

WALTER -WURST. 

